Dynamo-electric machine



O ct. 20, 1936e A. F. METZGER 2,058,339

DYNAMO-'ELECTRIC MACHINE Filed Sept. l2, 1935 Inventor-w A Lan E' Metgger,

Patented Oct. 20,` 1936 UNITED STATES DYNAMO-ELECTRIC MACHINE Alan F. Metzger, Swampscott, Mass., assignor to General Electric Company, a. corporation of New York Application September l2, 1935, Serial No. 40,262

12 Claims.

My invention relates to dynamo-electric mai chines and more particularly to an improved construction ol a magnetic l'leld structure for such machines.

lin certain types of dynamo-electric machines, it is desirable that the magnetic iiux traversing the air gap between that portion of the magnetic circuit oi the machine with which the magnetic field set un by the eld structure oi the machine `reacts and the held structure, should remain eulostantially constant. ln a battery charging gencrater, for example, the generator voltage should remain substantially constant, and the flux nro duced hy the field structure across the air gan ci the generator determines the regulation of the machine, other llactors remaining constant. Another example is, where it is desired that the operating sneed of an electric inotor shall re main substantially constant, and Where the speed is determined Toy the air gan flut, other factors remaining constant. The regulation et the air gap flux generally .has heen controlled hy c. variation in the excitation of the magnetic iield to compensate for variations in the resistance in the field exciting windings however, such systems have the general disadvantage of requiring a separate mechanism for conutrollingvv such excita" tion.

An ohject of my invention is to provide an irnproved magnetic eld structure which will in= hereutly compensate for the eiliect of temperature variations upon the operating character istics of a dynamo-electric machine. l accomzz plish hy providing a magnetic field structure in which a thermo-magnetic shunt is arranged toi/ary the air-gap flux, depending upon the temperature of the shunt. Preferably, this shunt is arranged between the main pole faces or between the noie faces and the frame to 1or0= vide a complete magnetic circuit, the reluctance of which is varied by the shunt, dependent upon the temperature or the field structure or of the field excitir t windings. The temperature of the shunt may he varied hy thermal conduction from the magnetic iield structure and radiation from the iield exciting windings or hy, a heating ele ment, such as a heating coil. Various magnetic alloys may he utilized which have the characteristic of changing their magnetic reluctance with temperature variations, such as a, ferro-nickel alloy of approximately 740% iron and 30% nickel, and it is desirable that the demagnetizing and remagnetizing hysteresis curves of such an alloy be close together for obtaining consistent results. Thus, the proper heating arrangement and choice (Cl. Til-223) of alloy provides for various compensating and compounding air gap magnetic edects. It is readily seen that with a temperature rise, a thermo-magnetic shunt may he made to increase its reluctance to such an extent that the decrease in the excitation of the field structure, due to the decrease in held current resulting from increased ileld resistance, will he compensated hy the dem crease in dus shunted from the air gap tlntough the thermo-magnetic shunt. also, it it is dem 'sii-ed to have a rising or drooping characteristic with temperature changes, the thermo-magnetic reluctance chareeteistic of the shunt or the heating arrangement utilized may he varied to provide tor a more rapid or slower increase, ree spectively, in the reluctance oi the shunt. leri= ous characteristics can also he obtained hy uti@ lining shunts of different transverse areas tor varying the effect of magnetic saturation on the shunt. ll also have found it desirable to nrovide a magnetically saturated section in the standard magnetic iield structure, so that the total reluctance oi the magnetic circuit will not he iiected materially hy the insertion of the shunt.

ldy invention he more fully set forth in the following description referring to the accom panylng drawing and the lectures ot novelty characterizing my invention will he pointed out with partieularity in the claims annexed and. forming a cert oi this specification.

For a hotter understanding ol' my invention, reference is made to the accompanying dra ing, wherein Fig. l is a front View oi' a dynamoelectrlc machine embodying my invention, in which thennoumagnetic shunts are arranged hetvveen adjacent main noie faces oi a stationary magnetic iield structure; Fig. 2 schematically illustrates a dynamo-electric machine wherein shunts, similar to those in Fig. l, are employed in connection with. a rotating magnetic eld structure; Fig. t illustrates another embodiment of my invention wherein thermo-gnetic shunts are arranged between eld pole faces and the magnetic frame of the machine; Fig. 4 illustrates another embodiment of myv invention wherein thermo-magnetic shunts are arranged completely around the air gan and bridge the entire eld poles 43. These eld poles are provided with pole faces 44 and a section 45 having a relatively low saturation point as compared with the remainder of the field poles, by being formed of a cross-sectional area less than the remainder of the pole structure. The field structure is excited by field exciting windings 46, which may be energized in any suitable manner, and the dynamo-electric machine is provided with a rotatable magnetic core structure 41 mounted upon a shaft 48 and arranged in spaced relation with respect to the pole faces 44,so as to provide an air gap therebetween. In accordance with my invention, the air gap flux is regulated by thermomagnetic shunts 49 arranged completely around the air gap and bridging all of the pole faces 44.

In view of the foregoing description, it will be seen that I have provided a magnetic field structure for a dynamo-electric machine wherein the effect of temperature variations upon the operating characteristics of the machine are inherently compensated, without requiring a separate mechanism for controlling the excitation of the machine.

Modifications of the arrangements, which I have described, will occur to those skilled in the art. I desire it to he understood, therefore, that my invention is not to be limited to the particular embodiments set forth, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A magnetic field structure for a dynamoelectric machine, a field exciting winding for said eld structure, means including a thermo-magnetic shunt in said magnetic iield structure for regulating the edect of temperature variations upon the excitation of said neld structure, and means dependent upon temperature variations of 'said field exciting winding including a heating coil for varying the temperature of said thermomagnetic shunt.

2. A magnetic eld structure for a dynamoelectric machine forming a complete magnetic circuit, said magnetic held structure having a magnetically saturatahlesect-ion under normally unsaturated conditions in the main portion of said iield structure, a field exciting winding for said held structure, and means dependent upon temperature variations of said field structure for varying the reluctance oi said complete magnetic circuit and for regulating the effect of temperature variations upon the excitation of said eld structure.

3. A magnetic field structure for a dynamoelectric machine forming a complete magnetic circuit, means including a section of cross-sectional area less than the remaindery of said magnetic eld structure for providing a magnetically saturatahle section, a field exciting winding for said field structure, and means dependent upon temperature variations of said iield exciting winding for varyingthe reluctance of said complete magnetic circuit and forly regulating the eiect oi temperature variations upon the excitation of said field structure.

d. A magnetic fleld structure for a dynamoelectric machine including a frameand a. plurality of field poles with faces arranged in ciring the effect of temperature variations upon the excitation of said field structure.

5. A dynamo-electric machine including a rotatable member'having a magnetic core structure, a magnetic field structure arranged in spaced relation to said magnetic core structure to provide an air gap therebetween, means including a field exciting Winding for said magnetic field structure for producing a magnetic flux in said air gap, and means dependent upon the temperature Variations of said magnetic field structure for regulating the effect of said temperature variations upon the magnetic flux in said air gap.

6. A magnetic field structure for a dynamoelectric machine having a plurality of eld poles, said field poles having pole faces arranged in circumferentially spaced relation, a eld exciting Winding for said field structure, and means including a thermo-magnetic shunt arranged between said pole faces for regulating the edect of temperature variations upon the excitation of said field structure.

'7. A magnetic held structure for a dynamoelectric machine including a frame and a plurality of field poles with faces arranged in circumierentially spaced relation, means including a section oi magnetic material in said eld poles having a relatively low saturation point as compared to the remainder of said field structure, a field exciting winding ior said iield structure, and means including thermo-magnetic shunts arranged between said pole pieces and said frame for regulating the elfect of temperature variations upon the excitation of said field structure.

d. A dynamo-electric machine including a rotatable member havinga magnetic core structure, a magnetic deld structure forming a complete magnetic circuit and arranged in spaced relation with said magnetic core structure to provide an air gap therebetween, said magnetic field structure having a magnetically saturatable section under normally unsaturated conditions in the main portion of said field structure, means inv cluding a field exciting winding for said magnetic held structure for producing a magnetic dux in said air gap, and means dependent upon temperature variations of said eld structure lor varying the reluctance of said complete magnetic circuit and for regulating the effect of temperature variations in said dynamo-electric machine upon the magnetic iiux in said air gap.

9. A dynamo-electric machine including a rotatable member having a magnetic core structure, a magnetic deld structure forming a coinplete magnetic circuit and arranged in spaced relation with said magnetic core structure to provide an air gap therebetween, means including a section in said magnetic field structure oi crosssectional area less than the remainder ot said magnetic field structure for providing a magnetically saturatable section under normally unsaturated conditions in themain portion of said field structure, means including a field exciting winding for said field structure arranged to produce a magnetic flux in said air gap, and means dependent upon temperature variations of said field exciting windings for varying the reluctance of said complete magnetic circuit and for. regulating the effect of said temperature variations upon the magnetic flux in said air gap.

10. A dynamo-electric machine including a rotatable member vhaving a magnetic core structure. a magnetic eld structure arranged in spaced relation to said magnetic core structure tc provide an adr-gap 'timmmiiwwim imm@ ciuding a held exciting winding mi fm netin field structure im pwiwng n l ux in said air gap, mea inhiding ihermiiw magnetic shunt, in said magnetic heid vii-maxim@ for regulating the effect nf temperatur@ wiuriam tions in said dynammelecmrim machin@ mimi magnetic flux in said air mi, and mmm; inw pendent upon temperature wwmtions mi' mi@ im exciting windings for varying the tenineminwtve mi said thermmmagnetic fahuni.

11. A dynamo-electric inwziiine. iiin'i rotatahin member having zu. magneti@ ww-if mirunw time, a magnetic eld structuur@ fminii plete 'magnetic circuit anni imfnngeii i n relation with said magneti@ wir@ :itrumiiimi vide an air gap therebelzwiiii immuni?, a Smitinn in said magnetic irucmiir semi/amai area less than Mii-2 i'iiimiiiii. magnetic field structure mit igmividiii;

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